Anthropogenic drivers of plant species coexistence in selected riparian systems, Kumawu district, Ashanti region (Ghana)

Abstract

Anthropogenic drivers have long been recognized as influencing species coexistence and the maintenance of biodiversity in riparian ecosystems among others. Despite their important role, riparian zones have been subjected to progressive alteration. This study aimed at evaluating how anthropogenic drivers influence plant species coexistence in riparian zones differing in scale of disturbance – intact zone (Amobia), slightly disturbed zone (Onwame), moderately disturbed zone (Ninian) and degraded zone (Pame), respectively, located in the Kumewu District of Ahanti Region (Ghana). Plots were randomly laid perpendicular to the anthropogenic gradients such as fire, grazing pressure, erosion, farming, animal trampling, bare ground and logging. Number of individuals was counted per plot and the percentage cover estimated per species. Species packing model was employed to quantify how competing species for resources coexisted, while Canonical correspondence analysis (CCA) was used to evaluate the effect of anthropogenic drivers on the variability of species assemblages. High number of species heterogeneity at Amobia riparian zone was a reflection of their tolerance to species coexistence than in the severely disturbed Pame riparian zone. However, species optimum and maximum probability of occurrence tend to be highest in Pame and lowest at Amobia riparian zone. This may be that widespread driver like fire, grazing pressure, farming and logging created conditions in gaps suitable for the recruitment of diverse species, with functional traits facilitating coexistence. These anthropogenic disturbances were responsible for 53.48% variability in species composition and coexistence. Thus, to enhance species coexistence, restoration of severely disturbed Pame, should be of priority concern by park managers.